COMBAT Experiment
Wave Optics of Deep Atmospheric Turbulence: From Underlying Physics towards Predictive Modeling, Mitigation and Exploitation
(AFOSR Multidisciplinary University Research Initiative Project)

Program Manager: Dr. Julie Moses

Research Problem. In order to facilitate the development of future long-range optical systems there is a need for understanding the performance of optical wave propagation along various atmospheric paths that may cross several extended (deep) regions of the atmosphere with quite distinctive spatial structures and temporal dynamics. Currently, analyses are performed in the framework of classical “fully developed” Kolmogorov optical turbulence theory describing the atmosphere as three dimensional boundless, statistically homogeneous and isotropic random fields of refractive index fluctuations and thus neglecting the impact of boundary conditions imposed by terrain and hydro-thermodynamic processes as well as of gravity and solar radiation induced buoyancy and friction forces that lead to formation of distinct, nearly horizontally aligned atmospheric layers with a rich variety of large-scale self-organized spatio-temporal coherent atmospheric structures including gravity and rotary waves, rolls, Bernard cells, jets, stratified flows, instabilities, etc. – effects that can severely impact optical wave propagation over long distances.

Technical Approach. The research will focus on elaborating a foundation for the physics of atmospheric optics effects in deep turbulence by building bridges between meteorology, computational fluid dynamics, and statistical wave optics that take into account the large-scale structural complexity of the atmosphere and mean optical characteristics of layered structures. The research team will develop a theoretical framework and the corresponding mathematical and numerical simulation tools that match small-scale meteorological features with optical wave propagation characteristics through high-resolution nested simulations and merge refractive and diffractive optics approaches in analysis of long-range propagation over the stratified atmosphere and highly anisotropic turbulence layers. For mitigation of atmospheric effects several new approaches will be evaluated: engineering of unconventional optical fields (e.g., with controllable space-varying coherence or dynamic phase and polarization patterns) and optical system architectures with reduced sensitivity to atmospheric distortions, including cascaded adaptive optics. The potential for exploitation of deep turbulence effects (e.g., optical wave-guiding or turbulence-induced diversity for compressive sensing/imaging) will be investigated.

Anticipated Outcome. The proposed research will provide a solid theoretical basis for optical wave propagation in deep turbulence conditions, lead to the development of practical computational tools for the realistic characterization assessment and prediction of beam projection and imaging over extended operational ranges, and provide an evaluation of approaches for mitigation and potential exploitation of deep-turbulence atmospheric effects.

Team. This program is a joint effort of the University of Dayton (Mikhail Vorontsov – Principal Investigator, Thomas Weyrauch, Ernst Polnau), the Air Force Institute of Technology (Steven Fiorino), Michigan Technological University (Michael Roggemann), North Carolina State University (Sukanta Basu), University of Miami (Olga Korotkova), and New Mexico State University (David Voelz).